Fluid shock absorber



July 2l, 1936. J. E. PADGETT l FLUID SHOCK ABSORBER Filed June 27, 19343 Sheets-Sheet 1 Tof/YEYS infill!!!vlllllllIl/Illd..1143!!!ItIlIltIIIHIIIIIIIIIIIII.

July 21, 1936.

J. E. PADGETT FLUID SHOCK ABSORBER Filed June 27, 1954 's sheets-sheet-zJuly 21, 1936. J. E. PADGETT FLUID SHOCK ABSORBER Filed June 27, 1954 3Sheets-Sheet 3 Muni-inl.

Patented July 2l, 1936 UNITED STATES i 2,043,285 FLUm snoei; AnsoannaJoseph E. Padgett, Toledo, Ohio, assignor, by mesne assignments, toGeneral Motors Corporation, Detroit, Mich., a corporation oi' 'Dela- WanY 'Application June 27, 1934, serial No. '132,639

246mm. (ci. iss-ss) This invention relates generally to fluid flow shockabsorbers, andmore particularly to an improved form of double actingshock absorber of this type.

Jli 'I'he principal object of this invention is to provide an improvediluid flow shock absorber which is of compact and economicalconstruction and which has very desirable loperating characteris-.

tics.

l Another object of the invention is to provide an improved fluid flowshock absorber vof 'the type having a working cylinder and a reservoir,and a restricted opening through which uid is forced to produce a shockabsorbing action, and

l5, wherein means is provided for causing the uid which is forcedthrough said restricted opening to be returned to the main body of fluidsubstantially without causing an air emulsion.

Still another object of this invention is to pro- `4vide an improvedshock absorber of the type having a cylinder substantially lled withfluid and a reservoir partially filled with fluid, and a restrictedopening for the cylinder at an elevation above the fluid level in thereservoir, and where.-

`-.in means is provided for directing or returning the fluid-which isforced through therestricted opening to the iluid of the reservoirsubstantially without causing an air emulsion.

-It is also an object of this invention to provide 'an improved shockabsorber having a cylinder substantially filled with fluid and apartially lled reservoir, wherein a piston operable in the cylinderdraws iuid into `the cylinder at one' end thereof and discharges fluidfrom the cylinder -through a restricted opening adjacent the other endof the cylinder, and wherein "means is -provided for returning the fiuidwhich is discharged through said restricted opening tothe main-body ofthe fluid in the reservoir substantially without causing an airemulsion. Other objects and advantages of this invention will beapparent from the following description, when taken in' conjunction withthe accompanying sheets of drawings, wherein v Fig.` l is a sideelevational view showing my improved shock absorber.

Fig. 2 is a longitudinal sectional view thereof taken substantiallyonline 2-2 of Fig. l'.

Fig. 3'is a transverse sectional view taken as indicated by line 3-'3 ofFig. 2.

Fig. 4 is a partial elevational Aview showing the sainel shock absorbercombination as is` shown in' Fig. 2, but with a different formof'clirectiiigV means for the restricted discharge of iluid from thecylinder.

Fig. 5 is a cross-sectional view taken as indicated by line 5-5 of Fig.4.

Fig. 6 is a cross-sectional view similar to Fig. 5 but showing anotherform of directing means for the restricted discharge fluid. 5

Fig. 7 is a longitudinal sectional view similar to Fig. 2 but showinganother shock absorber arrangement embodying my invention.

Figs. 8, 9 and 10 are partial sectional views showing other arrangementsfor the fluid direct- 10 ing means.

Fig. 11 is a sectional view showing the discharge restriction of Fig. 9on a larger scale.

Fig. 12 is a similar sectional view showing the restricted discharge of10 on an enlarged 15 scale;

Fig. 13 is an elevational view showing another form of the fluiddirectingmeans.

Fig. 14 is a sectional view thereof taken on line M-Il of Fig. 13. 4 20Fig. 15 is a sectional View similar to Fig. 2 but showing another shockabsorber embodying my g invention.` t Fig. 16 is a cross-section thereoftaken on line iii-,I6 of Fig. 15, and 25 Fig. 17 is a partial sectionalview showing the uid deflecting means as comprising abafile.

In the accompanying drawings, to which detailed reference will now bemade, I have shown improved uid iiow shock absorber of the 30 doubleacting type, wherein a very desirable shock absorbing characteristic isobtainable substantialiy without the formation of an air emulsion in theuid. It will be understood, of course, that `the novel combination of myinvention may be 35 embodied in various other structural arrangementsthan those illustrated in the drawings, and thatthe novel iluid 4iiowcontrol means of my invention may be embodied in many of the shockabsorber combinations of the prior art. o

The shock absorber illustrated in Figs. 1 and 2 of the drawings is adouble acting shock absorber, having a cylinder barrel lll in which areciprocating piston ii is operable, and a barrel i2 disposed around thccylinder barrel and spaced 45 therefrom to provide a fluid reservoir I3.The cylinder and reservoir barrels ill and i2 are connected at theirlower end with a closure plug I5 which` forms the lower end wall of thecylinder and reservoir. The opposite ends of the cylinder 50 andreservoir barrels are connected with a closure plus ii which forms theupper wall or end of the cylinder and'reservoir. 'I'he plug I6 may beprovided'with a suitable bushing I'lin which the piston actuating rod I8is slidable. 55

Ihe inner end of the rod I8 may be provided with a reduced portion I9 onwhich the piston Il is mounted and retained by means of the nut 20.

- The piston itself is provided with one or more .wardly in thecylinder.

openings 2l for the passage of fluid upwardly through the piston as thelatter is lmoved down- An annular` groove 22 may be formed in the uppersurface ofthe piston to connect the upper ends of the openings 2l. Anysuitable form of valve means may be provided on the piston forpreventing or limiting the flow through the piston, on its upwardstroke.v In this instance I show such valve means as comprising ashiftable plate 23` arranged to seat against the piston body inoverlying relation to the groove 22, so as to prevent a downward flowthrough the piston openings. A spacer 26 may be mounted on the pistonrod, with a stem portion 25 of the spacer serving as .a guide for thevalve plate, and with a flange portion 2B of the spacer serving as anabutment for a spring 21 which may be provided for normally urging thevaltv plate toward seating engagement with the pis n.

At or adjacent the lower end of the working cylinder I provide a passageconnecting the lower end of the cylinder with the lower end of thereservoir. This connection may be formed, in part, by an opening 29 and,in part, by a filling opening 30 formed in the plug member i5. A checkball 3| is arranged to control the connecting passage so that fluid mayflow into the cylinder from the reservoir, but cannot flow in thereverse direction. A suitable closure screw 32 may be provided in theouter end of the filling opening 30 to seal the same.

At or adjacent the upper end of the working cylinder I provide arestricted opening 34, which may be conveniently formed asa port in thecylinder wall I0 just inwardly of the closure plug I6.

VI'he restricted opening 3d allows fluid to be restrictedly dischargedfrom the working cylinder,

into the reservoir during movement of the piston, to thereby produce adesired shock absorbing action.

When my improved shock absorber has been charged with oil or othersuitable uid and is in an operating condition, the workingcylinder issubstantially filled with a solid body of the fluid and the reservoir I3is partially filled with the fluid. Since the restricted opening 3411slocated atv an elevation which would normally be above the level of thefluid in the reservoir I3, the fluid forced through the restrictedopening by the piston would be discharged at high velocity into therelatively large air space of the `reservoir before being returned tothe main body of fluid in the reservoir. I have found that such highvelocity discharge of fluid into the air space of the reservoir whilebeing returned to the main body of fluid usually results in the creationof an undesirable air emulsion.

Therefore, as an important feature of my invention, I have providedmeans for preventing the fluid, which is forced through the restrictedopening, from being released immediately and at high velocity intotheair space of the reservoir. which would otherwise result inagitation ofthe fluid and the creation of an undesirable air emul- Iaosaas brokenupjso diiiused'and withoutl themain body of reservoirfluidnbeingchurnedlinto an emulsion by the discharged; duid being dropped or pro-Jected thereinto.

In Fig. 2 of the drawings I have shown one 5 form of such directing orconducting means embodied in my shock absorber and comprising a 'tubularmember 35, which may besupported from the-closure plug IB insurrounding'relation to the cylinder barrel I0. This tubular memberandthe 10* cylinder barrel provide a space or passage. therebetween whichreceives the fluid discharged through the restricted opening 34 andreturns the discharged fluid to the main body of fluid in the reservoir.The size and shape of this space may 15 l be varied and, as shown inFig. 2may have an' annular chamber part 36 into which the opening 34discharges, and a shallow conduit part 35' for conducting or directingthe discharged fluid toward the main body of reservoir fluid. gli

The discharging of the fluid into the relatively small air space of thechamber 36 and the downward travel of the fluid in the conduit 38',causes the velocity of the discharged fluid to be dissi-l pated withoutpermitting the stream of fluid to 25 be broken up. In dissipating thevelocity of the fluid discharged through the opening 36, the tubus larmember 35-causes the fluid to spread out as a 4 v film in the shallowconduit 36 and to ow downwardly on the surfaces forming the sides ofthis 30 conduit. The effect of this action is to allow the dischargedfluid to be returned to the main body of fluid in the reservoir withminimum disturbance and with little or no emulsifying action.

The tubular member 35 may be made of a length 35 such that the velocityof the fluid discharged through the restricted opening 34 is dissipatedsufficiently to prevent an emulsifying action'. In some instances it maybedesirable to have the tubular member 35 long enough so that its lowerend will always be below the surface ofthe main body of fluid in thereservoir. This may not always be necessary, however. and in some cases,the tubular member may terminate above the surface of the reservoirfluid.

It is not necessary to my invention that the fluid directing anyvelocity. dissipating means, whichcooperates with the restricted opening34, be in the form of the tubular member 35 shown in Fig. 2, but may,for convenience of manufacture or from the standpoint of resultsobtained or other reasons', be of various other forms of construction.For example, in Fig. 4 of the drawings I have shown a portion of a shockabsorber combination which is identical with that of Fig. 2. but whereina small tube or pipe 40 is provided instead of the tubular member 35.The tube 40 is arranged with its upper end soldered or'l otherwiseretained in the restricted opening 34 and with its lower end extendingdownwardly in the a0 reservoir, and, terminating below the surface ofthe reservoir fluid. l

In Fig. 6 lof the drawingsI have shown another member d2, which may beapplied to the wail of the cylinder 63 to form a conducting and velocity65 dissipating passage M for the fluid which is dis, charged through therestricted opening 45. The member 42 may be a channel-shaped sheet metalmember which is closed atits upper end andis soldered or otherwisesecured tothe cylinder wall 70` to form a conducting passage similar tothat provided by the 'tube 40 of Fig. 4. A L v To prevent the loss offluid from the cylinder through the piston rod bushing l1 of Fig. 1Iprovide the closure plug le with a leakage coilventing the entry of dirtor other foreign matter.

The closure plug It may be provided with a connecting eye i forattaching the lower end of the shock absorber to a bracket 52 of thevehicle-chassis, and likewise the upper end of the piston rod it may beprovided with a suitable eye b3 which is adapted to be connected to abracket Et of the vehicle chassis. If desired, a tubular .dust guard 5dmay be mounted on the eye 53 to extend downwardly in telescopingrelation around the reservoir barrel I2.

In the operation of the device illustrated in Fig. 2, the piston Hismoved downwardly in the cylinder when the axle and vehicle body approacheach other. During-this downward stroke the piston is moved toward whatmay conveniently c be called the low pressure end of the cylinder andcauses the check ball 3i to be seated. The iluid contained in thecylinder below the piston is thus forced upwardly through the pistonopenings 2i and past the valve plate 23 which is unseated by the ow ofiluid. The movement of the piston rod it into the .cylinder also causessome fluid to be displaced from the cylinder, and since the check ball3i is seated on the down stroke of the piston the rod displacement mustbe discharged through the restricted opening di. The shock absorbingaction produced on the down stroke of the piston vis thusobtained inpart from 'the resice to dow of fluid upwardly through the pistonopenings and past the valve 23, and in part from the restricteddischarge of the huid displaced by the rod it. The degree of shockabsorbing action desired on the downward stroke of the piston may` beobtained by appropriately selecting, the size and number of the pistonopen ings 2 l, as well as the resistance which the valve plate 23 is toofferto the upward ilow of iluid, and also by appropriately selectingthe area of the restricted opening 34. Y l

When the vehicle body and axle separate, the piston il is moved upwardlyin the cylinder to- -ward the high pressure end thereof and, during thisupward or rebound stroke, the valve plate 23 is seated against thepiston and the fluid trapped in the cylinder above the piston isdischarged through the restricted opening' into the reservoir. The areaoil the restricted openthe provision of these two restricted openingsproing u is the main factor in determining the shock absorbing actionwhich is obtained on the upward stroke ol the piston. The upward strokeoLthe piston also allowsor causes the check ball Il to be unseated and arelatively tree return ilow v of iluid takes place from the reservoirintothe4 cylinder through the passage 29, SII.

In Fig. 'I of the drawings I have shown a shock absorber which isgenerally similar to that illustrated in Fig. 2, but wherein the checkvalve plate l0 of the piston 6| may be provided with a restrictedopening 62 and wherein the lower end otthe working cylinder 63 may belprovided with a restricted opening 64 which communicates with the lowerend of the reservoir 65. Aside from the restricted openings G2 and M,the` shock absorber o1 Fig. 7 is the same as the shock absorber shown inFig. 2, but, as will be explained hereinafter,

duces a somewhat diierent shock absorbing funciluid discharged throughthe restricted opening fn enters a relatively small air space and itstion than is obtained from the shock absorber of Fig. 2

Assuming that the shock absorber of Fig. 'i has been charged with iiuidand is in operating condition, the downward movement of the pistoncauses some of the fluid which is contained in the cylinder below thepiston to be forced upwardly through the piston openings 6G and past thevalve plate 6G which is unseated by the dow of iluid and also causessome of the duid, con tained in the cylinder below the piston, to bedischarged into the reservoir through the restricted opening 6d. Inaddition to this, the duid which is displaced from the cylinder by thepiston rod 61 moving thereinto, is discharged either through 15` arestricted opening 68 corresponding with the restricted opening 3d ofthe shock absorber of Fig. 2, or through the restricted opening t4, orpartly through each of the openings 66 and 68.

Thus it will be seen that as the piston moves 20 downwardly toward thelow pressure end of the cylinder, a shock absorbing action is obtainedby the restricted discharge of iiuid through the openings Bd and 58,-andby the resistance which the piston openings 66 and the valve plate Etoiler 25 to the iiow of fluid upwardly past the piston.

During the rebound stroke of the piston or, in

other words, during movement of the piston toward the upper or highpressure end of the cylinder, the valve plate Sil is seated against the30 I piston body and the iiuid which is trapped Vin the cylinder abovethe piston can be discharged only through the restricted opening t2 andthe restricted opening @8. The restricted discharge of fluid throughthese openings produces a shock 35 I absorbing action the value of whichis determined largely by the combined area of these two restrictedopenings.

During the downward stroke oi' the piston described above, the checkvalve 69 is seated to prevent uid from being displaced into thereservoir through the opening 10 and on the upward stroke of the pistonthe check valve 69 is unseated to allow a relatively free return ilow ofiiuid froml the reservoir into the cylinder.

A tubular member 1I, similar to the tubular. member 35 of the shockabsorber of Fig. 2, may be disposed around the cylinder barrel 63 toprovide a conducting and velocity dissipating passage. or chamber 12which receivesthe iluid discharged through the restricted opening 88 andretums the same to the main body of the reservoir nuid so that, asexplained above, an objec-` tionable emulsifying action is eliminated.

If desired, the fluid directing means may be in lwhich as shown in Fig.8, may be mounted on the upper closure plug 15 and arrangedto extenddownwardly around the cylinder barrel' 1B. The tubular member is of suchdiameter that a space or chamber 11 is provided between the same and thecylinder to receive the fluid discharged through the restricted opening18; The size and shape of this space'or chamber is such that thevelocity is dissipated therein without the stream of huid having anopportunity to form an air emulsion.

member 1I may be deflected inwardly to engage the cylinder barrel 16 tothereby form a closure for the lower end of this chamber, in which oasean opening 19 of suitable size and shape may be 75 provided-through thelower portion. of the tubu\ lar member, preferably on the side thereofopposite the restrictedopeni'ng 18. The opening .19 may beformedasas'lot or cut-away portion or as' a radiallyfbulged portion,which as the case may.be ,j,exten`ds for a .short distance circum- 'vlferentiallyoi.' the member 14.` The open lower l end'of thechamber 11or the opening 19 thereoi, asthe may be, allowsthe iluid whichhas beendischarged into the chamber to iiow downwardly as a on the surface ofthecylinder 19 into the reservoirilui l l In Figa-9 and ",-11 of thedrawings Ihave shown a'uid4 conducting and velocity dissithin edgedoriiice 82. This orice maybel con.

veniently formed in a plug member 03, which is retained in the openingof the tubular member, such as by counterboring the plug member 83 fromone or both sides thereof so as to leave a l so' thin .weblof materialthrough which the orifice 92 is formed. The provision of such a thinedged orifice in the restricted cylinder opening allows the restricteddischarge of uid to take place substantially independently of viscositychanges in the fluid. The elimination .of viscosity ef.- feots in therestricted cylinder opening is very desirable because it permits a moreuniform shock absorbing action to be obtained. It should be understood,that the restricted cylinder openings in any of the shock absorbersherein described may be constructed or provided with a thin edged oriceso that the beneiloial effects explained in connection with theconstruction of Figs. 9 and 1l may be obtained.

In the caseof some shock absorbers embody` ing my invention it may bedesirable to provide the restricted opening -at the high pressure end ofthe cylinder with a-check valve `or iluid pressure actuated valvearranged to open toward the reservoir. Suche valve may be desirable toprevent the discharge of iluid from the cylinder until the pressuretherein has built up to a desired predetermined value. a

In Figs.' l0 and 12 ofthe drawings I have shown such-.a check` valve 05associated with the 'restricted opening 86` at the high pressure endofthe cylinder and arranged lin the uuid ,conducting and velocitydissipating passage 81 which communicateswithgthe restricted open- `ing.Any suitable form ofcheck valve may be used for this purpose and, `inthis instance, I show a check valve 05, which is constructed as a unitand is mounted in the-upper .end of a tubular member 08 which may besimilar to the tubular member 40 oi Fig. 4.- l

The check valve feature :lust described may, if desired, be used inconjunction with the restricted cylinder opening'` and uid conductingmeans of any of the shock absorber arrangements herein disclosed.

When the defiecting or conducting means is constructed `as a small tubeor pipe, as shown in Figs. 4 to 6 inclusive and 9 to 12 inclusive, it isdesirable'that the tube extend into the body lof reservoir fluid -sothat the iluid discharged throughthe tube will not drop upon or be pro-Jected against the surface of the reservoir fluid. If the conductingtube or pipe. such as the pipe 94, terminates above the surface of thereserf voir iiuid. it is desirable that the tube be provided at itsdischarge end with a deiiector or spreader part such as the deector part90 shown in Figs. 13 and 14.` This deilector part may have any desiredshape or location such that it will cause the i'luid` to form a filmonvthe surface of the cylnder barrel 90 and thus 'permit the dischargeduid to return to the reservoir fluid without causing an emulsion. Asshown in Figs. 13 and 14, this deilector part may be formed byflattening or bending' the lower end of the tube and thereby giving it ashape which is capable oi `producing the ,desired result.

In Figs. 15 and 1'6` of "the drawings I have shown 'a shock: absorber ofthe type illustrated in Fig. 2, but having spring loaded valves for thepiston and the restricted opening |0|. The valve |02 for the restrictedopening |0| may be a check valve such as that illustrated in Fig. 12.The spring loaded valve for the piston may be of any. suitableconstruction, forexample it may be a diskfvalvertructure |03 as hereinillus- 692.628,-*i1led Qctober "I, 1933, but for purposes of thelpresent disclosure this valve comprises a rigid disk |04 having one ormore holes therethrough and a ilexible disk |05 which controls the holesof the rigid disk and is adapted to be ilexed by the iiuid pressureacting through the holes of therigid disk on the up stroke of thepiston. vExcept forfthe valves |02 and |03 and the conducting'pipe |08,the shock absorber of Fig.` 151s similar to the shock absorber of Fig. 2and the corresponding partsare designated in Figs. 15 and 16 by primedreference characters.

-Instead of constructing thedeflecting means as a tubular memberextending around the cylinder as shown in Figs. 2, 'I' and 8, it may besimply a baille plate of such extent and shape as is needed to cause thevdischarged fluid to be spread out into a film while ,it is beingreturned tothe reservoir fluid. In Fig. 17 of the drawings I have showna baille plate 90 of this character which is curved to extend only apart of the way around the cylinder 9|. The duid which is discharged.through the opening 92 is baffled and spread out as a nlmjon the wallof the cylinder and is returned to the reservoir fluid substantiallywithout emulsincation.

tratecL The piston valve |03 is more fully disf :closedl in copendingapplication Serial No.

From the foregoing description and accom-l panying drawings it will newbe readily seen that I have 'provided a novel shock absorber combinationwhich is of very economical construction and which is capable ofrendering very satisfactory and eilicient service. It will beunderstood, furthermore, that the improved shock absorber that I haveprovided includes a restricted discharge opening at the high pressureend of the cylinder and means for returning the iiuid, which isdischarged through the restricted opening, to the main body of the fluidsubstantially without objectionable emulsiiication of the iluid.

Having thus described my invention, I claim:

1. In a shockabsorber the combination of a housing having a .pluralityof chambers therein, a body of fluid in said housing substantiallyfilling one of said chambers and partially illling the other, saidhousing having a restricted opening therein at an elevation above thelevel of the fluid in the partially iilled chamber, means for forcingiluid through said restricted opening, and means :imacat for spreadingthe restrlctedly discharged uid out into substantially a iiim andthereby returning such iluid to the main body of fluid substantiallyWithout forming an air emulsion.

2. In a shock absorber the combination of a housing having therein acylinder and a reservoir, uid in said cylinder and reservoir, a pistonin. said cylinder for cooperating with the duid, said cylinder having arestricted opening through which fluid may be forced by the piston, andmeans cooperating with a wall of the reservoir for causing the fluidwhichis forced through said restricted opening to be spread out intosubstantially a film and returned to the reservoir iluid substantiallywithout causing an air emulsion.

3. In a shock absorber the combination of a housing having therein acylinder and a reservoir, a body of uid in the housing substantially`filling said cylinder and partly lling said reservoir, a piston in saidcylinder for cooperation with the fluid, a check valve associated withthe piston, said cylinder having a restricted opening through whichfluid is forced by the pistonsaid 'cylinder opening being above the uidlevel in the reservoir, and means cooperating with at least a portion ofthe wall of the cylinder for providing a conduit for returning the fluidwhich is disfcharged through said restricted opening to the reservoirduid substantially without causing an air emulsion.

4. In a shock absorber the` combination of a housing having therein alcylinder and a reservoir, n. body of duid in the housing substantiallyfilling said cylinder and partly fi; a said reser- 'voi'r, arestrictedopening in the oder above the level of the fluid in the reservoir, avalved piston operable in said cylinder and adapted to force iiuidthrough said restricted opening, means providing for a return flow ofuid into the cylinder at a point spaced from said restricted opening,and means cooperating with atleast a portion of the wall of the cylinderfor returning the 'fluid which has been forced through the restrictedopening to the reservoir duid substantially as a film and withoutcausing an air emulsion.

5. In a shock absorber the combination of a housing having therein acylinder and a reservoir, a body of fluid in the housing substantiallynlling "the cylinder and partially filling said reservoir, a vrestrictedopening in the cylinder above the level I of the fluid in the reservoir,a piston operable in said cylinder and adapted to force fluid throughsaid restricted opening, a check valve arranged `to return uicl to thecylinder from the reservoir,

a check valve on said piston arranged to seat on movement oi the pistontoward the restricted opening, and fluid directing means in thereservoir for returning the iluid discharged through said restrictedopening to the reservoir fluid.

. 6. In a shock absorber the combination of a cylinder having a highpressure end and a low pressure end, areservoir, iiuid in said cylinder.and reservoir, said cylinder having a restricted Aopening communicatingwith'the high pressure *end thereof. a piston operable in said cylinder.the same to the reservoir uid.

'1. In a 'shock absorber the combination of' a cylinder having s highprsure end and a low pressure end, a reservoir, iluid in said cylinderand reservoir, said cylinder having a restricted. opening communicatingwith the high pressure end thereof, a piston operable in said cylinderfor forcing iiuid through the restricted opening into the reservoir,means adjacent the low pressure end of the cylinder for admitting fluidto the cylinder from the reservoir but preventing iiow in the reversedirection, and means in the reservoir cooperating with said restrictedopening for returning the fluid discharged therethrough to the reservoiriluid substantially without causing an emulsion.

8. In a shock absorber the combination of a cylinder having a highpressure end 'and a low pressure end, a reservoir, uid in said cylinderl and reservoir, said cylinder having a restricted openingcommunicatingwith the high pressure end thereof, a piston in saidcylinder, a rod extending into the high pressure end of the cylinder foractuating the piston, said piston being effective for forcing iuidthrough said restricted opening upon movement of the piston toward thehigh pressure end and said rod being effective for ldisplacing uidthrough said restricted opening the level of the uid in the reservoir, apiston operable in said cylinder and adapted to force fluid through saidrestricted opening, a check valve for returning fluid to the cylinderfrom the reservoir below the piston, said restricted opening being athin-edged orifice, and means for dissipating the velocity of the fluiddischarged through said orifice to decrease the tendency to create anair emulsion.

10. In a shock absorber the combination of a housing having therein acylinder and a reservoir, a body of uid in the housing substantially'filling the cylinder and partially lling the reservoir, a restrictedopening in the. cylinder above the level of the uid in the reservoir, apiston operable in said cylinder and adapted to force fluid through saidrestricted opening, a check valve for returning iluid to the cylinder'from the reservoir below the piston. means in the reservoir providing aconduit for returning the uid, which `is discharged through saidrestricted opening, to the reservoir fluid, and a check valve vcontrolling the flow through said restricted opening and arranged toopen toward the reservoir. Y l1. In a shock absorber the combination ofa housing having therein a cylinder and a reservoir, a body of uid inthe housing substantially lling the cylinder and partially filling thereservoir, a restricted opening in the cylinder above the level of theuid in the reservoir, a second restricted opening connecting thecylinder and reservoir ata point remote from the first mentionedrestricted opening, a pistonv in the cylinder between the restrictedopenings and operable to force fluid through the same into the lreservoir, a check valve associated with the second restricted openingto permit a relatively 'free returnflow of fluid into the cylinder, andmeans for dissipating the velocity of the fluid discharged through thefirst mentioned restricted opening f 12. In ashock absorber thecombination of a housinghaving therein a cylinder and a reservoir, abody of fluid in the housing substantially filling the cylinder andpartially filling said reservoir, a restricted opening in the cylinderabove the level of-the uid in the reservoir, a piston operable in saidcylinder and adapted to force A uidthrough said restricted opening, acheck Y valve arranged to return uid to the cylinder from the reservoir,valvemeans on said' piston,`

arranged to permit a relatively freer flow of uid past the piston onmovement of the same away from said restricted opening and a relativelymore restricted ow past the piston on movement of the same towardvsaidrestricted opening, and means for returning the fluid which isdischarged through said restricted opening to thereser'voir uidincluding means for reducing the velocity of such discharged uid.

13. In a shock absorber the combination of a housing having therein acylinder and a reservoir, a body of fluid in the housing substantiallyfilling the cylinder and partially filling the reservoir, a restrictedopening in thecylinder above the level of the iiuid in the reservoir, asecond restricted opening connecting the cylinder and reservoir at apoint remote from the rst mentioned restricted opening, a piston in thecylinfluid discharged through the ilrst mentioned restricted opening.

14. In'a shock absorberl the combination of. a housing having therein acylinder and a reservoir, a body of fluid substantially filling saidcylinder and partially filling said reservoir, said cylinder having arestricted opening communicating with the reservoir below the surface ofthe reservoir fluid and a restricted opening com.

municating with the reservoir about the surface ofthe reservoir fluidi apiston operable in said cylinder and adapted to force iiuid through oneof said openings on movement in one direction land through the otherrestricted opening on movement in the other direction, and meanscooperating with the second restricted opening for returning the fluidwhich is discharged therethrough to the reservoir fluid substantiallywithout creating an-air emulsion. 15. In a shock absorber thecombination of a housing havingtherein a cylinder and a reser'- hvoir,fluid in said cylinder and reservoir, said cylinder having a restrictedopening adjacent the high pressure end thereof, a piston operable insaid cylinder for forcing fluid through said restricted opening, meansfor returning fluid to the cylinder-'from the reservoir below thepiston,

and means for returning the iiuid which is discharged through therestricted opening to the reservoir fluid .including means providing avelocity dissipating chamber communicating with said restricted opening.

16. In a shock absorber the combination of a housing having therein acylinder and a reservoir, 'fluid in said cylinder and reservoir,'saidadsense cylinder having a restricted opening adjacent the highpressureend thereof. a piston operable in said cylinder for forcingfluid through said restricted opening, means for returning fluid to thecylinder from the reservoir-below the piston. l means providing achamber arranged to receive fluid discharged through said restrictedopening,

. and means providing a passage for conducting the discharged fluid fromsaid chamber tothe reservoir uid. l1

Y 17. In a shock absorber the combination of a housing having therein acylinder and' a reservoir, iiuidin said cylinder and reservoir, saidcylinder having a restricted opening adjacent thehigh pressure endthereof, a'piston operable 14 in said cylinder for forcing iluid throughsaid restricted opening, means for returning fluid to the cylinder fromthe reservoir below the' piston, and means for dissipating the velocityof the dis- 1 charged fluid and returning the fluid to the reset- 21voir fluid including means cooperating with the restricted opening tocause the discharged fluid to be spread out into substantially a film.

18. In a shock absorber -the combination of a housing having a cylindertherein and a reservoir 2, around the cylinder, uid in saidcylinder andreservoir, said cylinder having a restricted opening adjacent its upperend, a piston operable in said cylinder for forcing fluid through saidrestricted opening into the reservoir, means pro- 31 viding for a flowof fluid into the cylinder from the reservoir below the piston, andtubular means disposed around said cylinder and adapted to direct thefluid, which is discharged through the relsitdr'icted opening, towardthe .body of reservoir 8i il 19. In a shock absorber the combination ofa housing having a cylinder therein and a reservoir around the'cylinder, iiuid in said cylinder and reservoir, said cylinder having arestricted open- 4 ing adjacent its upper end, a piston operable in saidcylinder for forcing uid through said restricted opening into thereservoir, means providing for a ow of uid into the cylinder from thereservoir below the piston, and tubular means 4 disposed around saidcylinder with a space therebetween for returning the uid, which isdischarged through the restricted opening, to the reservoir fluidsubstantially without causing an air emulsion. li

20. In a shock absorber the combination of a housing having a cylindertherein and a reservoir around the cylinder, fluid in said cylinder andreservoir, said cylinder having a restricted opening adjacent its upperend, a piston operable in c said cylinder for forcing uid through saidre. stricted opening into the reservoir, means pro- A viding for a iiowof fluid into the cylinder fromA the reservoir below the piston, atubular member disposed around said cylinder with a space thereebetween, and means supporting said tubular member such that the uiddischarged through said restricted opening must travel through at leasta portion of said space to reach 'the body of reservoir iluid. 6

2l. In a shock absorber the combination of a' housing having a cylindertherein and a reservoir around the cylinder, fluid in said cylinder andreservoir, said cylinder having a restricted opening adjacent its upperend, a piston operable in 71 said cylinder for forcing iiuid throughsaid restricted opening into the reservoir, means providing for a flowof fluid into the cylinder from the reservoir below the piston, atubular member disposed around said cylinder with a space there 1lbetween, and means substantially closing said tubular member at theupper end thereof whereby the iluid which is discharged through saidrestricted opening is prevented, from returning to the reservoir fluidexcept through said space.

22. In a shock absorber the combination of a cylinder having a highpressure end and a low pressure end, areservoir, fluid in said cylinderand reservoir, means providing a ow restricting passage connecting saidhigh pressure end -and said reservoir,'means providing a constantly lopen flow restricting passage connecting said low pressure end and thereservoir, a piston operable in said cylinder and adapted upon movementin one direction to force iiuid through the irst mentioned restrictingpassage and upon movement in the opposite direction to force fluidthrough the second mentioned constantly v open restricting passage, andvalve means adjacent the low pressure end supplementing the secondmentioned constantly open restricting passage to permit a relativelyfree additional return ow of uid from the reservoir into said lowpressure end.

23. In a shock absorber the combination of a cylinder, a reservoir,fluid in the cylinder and reservoir, means providing a constantly openflow restricting conduit connecting each end of the cylinder withthereservoir and communicating with the reservoir below the level of thefluid therein, a. double acting piston operable in said cylinderl forproducing a shock absorbing action and adapted upon movement in onedirection to force uid' through one constantly open restricting conduitand upon movement in the other direction to force fluid through theother constantly open restricting conduit, and a check valvesupplementing the constantly open restricting connection at one end ofthe cylinder and operable to permit a relatively free additional returnW of fluid from the reservoir.

24. In a shock absorber the combination oi' a cylinder, a reservoir,iluid in the cylinder and reservoir, means providing a constantly openflow restricting conduit connecting each end of the cylinder with thereservoir and communicating with the reservoir below the level of thefluid therein, a double acting piston operable in said cylinder forproducing a shock absorbing action and adapted upon movement in onedirection to force fluid through'one restricting conduit and uponmovement in the other direction to force fluid through the otherrestricting conduit, a. check valve on said piston, and a check valvesupplementing the restricting connection at one end of the cylinder andoperable to permit a relatively free return now of fluid from thereservoir in addition to the restricted flow provided by said otherrestricting conduit.

JOSEPH E. PADGEI'I.

